An example scheme of inspecting a flowability of a blood and a condition of a cell in the blood is a scheme of using a blood filter (see, for example, patent literatures 1 and 2). The blood filter includes a substrate formed with minute grooves and another substrate is joined with that substrate. When such a blood filter is used, a velocity when a blood passes through the grooves can be measured, or a condition of a cell in the blood when the blood passes through the grooves can be observed.
FIG. 28 is a piping diagram showing an illustrative blood inspecting apparatus using the blood filter. A blood inspecting apparatus 9 includes a liquid feeding mechanism 91, a liquid discharging mechanism 92, a blood supply mechanism 93 and a flow rate measuring mechanism 94.
The liquid feeding mechanism 91 is for supplying a predetermined liquid to a blood filter 90, and includes liquid reserving bottles 91A, 91B and a liquid feeding nozzle 91C. The liquid reserving bottle 91A reserves an isotonic sodium chloride solution for measurement. The liquid feeding mechanism 91 has the liquid reserving bottle 91 B for reserving a distilled water for rinsing. According to this liquid feeding mechanism 91, as a three-way valve 91D is switched accordingly with the liquid feeding nozzle 91C being attached to the liquid filter 90, a state in which the isotonic sodium chloride solution is supplied to the liquid feeding nozzle 91C and a state in which the distilled water is supplied to the liquid feeding nozzle 91C can be selected.
The liquid discharging mechanism 92 is for discharging a liquid in the blood filter 90, and includes a liquid discharging nozzle 92A, a pressure-reduction bottle 92B, a pressure-reduction pump 92C and a liquid discharging bottle 92D. According to this liquid discharging mechanism 92, as the pressure-reduction pump 92C is actuated with the liquid discharging nozzle 92A being attached to the blood filter 90, the liquid in the blood filter 90 is discharged in the pressure-reduction bottle 92B through a piping 92E. The liquid in the pressure-reduction bottle 92B is discharged in the liquid discharging bottle 92D through a piping 92F by the pressure-reduction pump 92B.
The blood supply mechanism 93 is for supplying a blood to the space formed by suctioning a liquid from the blood filter 90, and includes a sampling nozzle 93A.
The flow rate measuring mechanism 94 is for obtaining information necessary for measuring a speed of a blood travelling through the blood filter 90, and includes a U-tube 94A and a measuring nozzle 94B. The U-tube 94A is connected to the blood filter 90 by a piping 94C. The U-tube 94A is filled with a liquid, while the piping 94C is filled with air. A blood in the blood filter 90 is travelled by a water head difference between the blood filter 90 and the pressure-reduction bottle 92B.
According to the blood inspecting apparatus 9, a traveling time of a blood is measured as follows.
First, as shown in FIG. 29, the interior of the blood filter 90 is replaced with an isotonic sodium chloride solution. More specifically, the liquid feeding nozzle 91C of the liquid feeding mechanism 91 is attached to the blood filter 90, and the three-way valve 91D is switched so that an isotonic sodium chloride solution in the liquid reserving bottle 91A can be supplied to the liquid feeding nozzle 91C. On the other hand, the liquid discharging nozzle 92A of the liquid discharging mechanism 92 is attached to the blood filter 90, and the pressure-reduction pump 92C is actuated. Accordingly, the isotonic sodium chloride solution in the liquid reserving bottle 91A is supplied to the blood filter 90 through the liquid feeding nozzle 91C, and a waste liquid in the blood filter 90 is discharged in the liquid discharging bottle 92D through the liquid discharging nozzle 92A and the pressure-reduction bottle 92B.
Next, the liquid feeding nozzle 91C is detached from the blood filter 90, and as shown in FIG. 30A, some of the isotonic sodium chloride solution in the blood filter 90 are suctioned by the sampling nozzle 93A of the blood supply mechanism 93, and as shown in FIG. 30B, a space 95 for retaining a blood is formed.
Furthermore, as shown in FIG. 31A, a blood is collected from a blood collecting tube 96 by the sampling nozzle 93A, and as shown in FIG. 31B, a collected blood 97 is filled in the space 95 of the blood filter 90.
Subsequently, as shown in FIG. 32A, the measuring nozzle 94B of the flow rate measuring mechanism 94 is attached to the blood filter 90. Accordingly, as a water head difference caused between the blood filter 90 and the pressure-reduction bottle 92B, the blood in the blood filter 90 travels, and a liquid-level position in the U-tube 94A changes. According to the blood inspecting apparatus 9, as shown in FIG. 32B, a change speed of the liquid-level position in the U-tube 94A is detected by plural photo sensors 97, and based on the detection result, a travel time of the blood is calculated.
According to a scheme of connecting the U-tube 94A and the blood filter 90 together, however, because the liquid-level position in the U-tube 94A changes, a measurement pressure (a pressure which acts on the blood 97 in the blood filter 90) varies. Moreover, in order to cause the blood 97 to travel in the blood filter 90 by water head difference, it is necessary that the pipings 92E, 94C from the U-tube 94A and the blood filter 90 to the pressure-reduction bottle 92B must be filled with a liquid. Accordingly, because a relatively-long piping length is requisite, the piping resistance becomes large. Furthermore, in addition to the liquid feeding nozzle 91C and the liquid discharging nozzle 92A, the measurement nozzle 94B for connecting the U-tube 94A and the blood filter 90 is requisite, the number of nozzles necessary for a measurement becomes large. What is more, because the number of nozzles is large, the piping becomes complex, and the number of valves for switching the nozzles 91C, 92A, 93A, and 94B becomes large, so that the number of parts is large. This prohibits the miniaturization of the apparatus. The more the number of parts is, the more the number of parts like a valve which has a relatively large failure rate becomes, so that the mean-time-between-failure (MTBF) which is an index expressing a failure rate (performance) of the apparatus becomes short.
Moreover, according to a scheme of suctioning the isotonic sodium chloride solution from the blood filter 90 by using the sampling nozzle 93A before a blood is supplied to the blood filter 90, it is necessary to frequently switch the nozzles 91C, 92A, 93A, and 94B to use, so that a measurement time becomes long. In particular, in order to control the suction amount of the isotonic sodium chloride solution in an appropriate amount, it is necessary to suction the isotonic sodium chloride solution while appropriately monitoring the liquid level in the blood filter 90, so that it takes a lot of time for suctioning of the isotonic sodium chloride solution.
Furthermore, filling of the isotonic sodium chloride solution in the blood filter 90 is carried out by using the pressure-reduction pump 92C of the liquid discharging mechanism 92. However, air bubbles are likely to be mixed in the blood filter 90 by suctioning merely from the downstream side of the blood filter 90. In order to overcome such problem, it is necessary to cause the isotonic sodium chloride solution to flow into the blood filter 90 for a relatively long time by a high negative pressure. In this case, the amount of isotonic sodium chloride solution used becomes large, which is uneconomical, and the electric power consumption of the pressure-reduction pump becomes large, which is disadvantageous from the standpoint of a running cost.
Patent Literature 1: Unexamined Japanese Patent Application KOKAI Publication No. H02-130471
Patent Literature 2: Unexamined Japanese Patent Application KOKAI Publication No. H11-118819